Many washing or cleaning agents comprise sensitive ingredients, such as e.g. fragrances. The disadvantage is that these types of ingredients that are incorporated in such agents frequently lose their activity during storage and/or their activity is at least strongly diminished before the desired time of application, namely by chemical reactions as a result of interactions with other ingredients of the washing or cleaning agent and/or due to physical factors. On these grounds an encapsulation of the ingredients can be advisable.
Numerous commercial encapsulation systems already exist which are based on natural or synthetic polymers. They can enclose an active agent or its solution and then be physically or chemically crosslinked in the shell or be precipitated out with another polymer by a coacervation process. Other encapsulation methods by liposomes exist, e.g. “Nanotopes” from Ciba-Geigy, or sponge-like particles such as “Microsponges” from Advanced Polymer Systems. Micro-encapsulated molded objects, for example, are employed to increase the stability of pharmaceutical active agents, to influence taste, for the release of active agents targeted at specific organs and to avoid incompatibilities with other adjuvants and active agents. Moreover, microcapsules are used in adhesive technology. Furthermore, fragrance capsules are also known with gelatin as the wall material, from which the perfume oils are released by means of mechanical destruction. Apart from “real” microcapsules that possess a shell/core structure, there exist spherical carrier particles e.g. of alginate, gelatin or polyvinyl alcohol (PVAl) into which an active agent, living cells or enzymes can be embedded. These capsules can be manufactured e.g. by a prilling process. In general microcapsules are particles with a diameter of <1 mm. Besides the inclusion in capsules of various sizes, substances can also be adsorbed onto suitable carrier materials or be chemically modified.
Microcapsules that can comprise liquid, solid or gaseous substances as the core material are known from the prior art. For example, phenol-formaldehyde polymers, melamine-formaldehyde polymers, polyurethane, gelatin, polyamides or polyureas can be used as the material for the capsule walls.
Washing or cleaning agents that comprise microcapsules are also known. Due to their particular stability, microcapsules made of melamine-formaldehyde resins have proven their worth in washing or cleaning agents. There is, however, a problem, in that in the manufacture of these microcapsules, the obtained capsule dispersions basically still include residual free formaldehyde, the presence of which, in further processing or in the end product that is supplied to the consumer, is undesirable. Consequently, the patent literature contains proposals to lower the formaldehyde content by adding formaldehyde scavengers.
EP-A 0 415 273 describes the manufacture and use of mono and polydisperse solid spherical particles of melamine-formaldehyde condensate. The use of ammonia, urea or ethylene urea is proposed so as to bind the formaldehyde released during the condensation.
The formaldehyde content of the dispersion is usually lowered by adding the cited formaldehyde scavengers to the microcapsule dispersion or during the manufacture of the microcapsule dispersion. However, the formaldehyde content of products that comprise this type of microcapsule dispersions or which are treated with them, often cannot be reduced below a certain level—even by adding large quantities of formaldehyde scavengers.
Therefore, the object of the present invention was to provide microcapsule-containing washing or cleaning agents that comprise microcapsules, which involve the lowest possible amount of formaldehyde or in which the use of formaldehyde for microcapsules is preferably totally avoided.
It was surprisingly found that certain capsule materials in washing or cleaning agents provide exceptionally stable capsules and moreover totally exclude contamination of the washing or cleaning agent with formaldehyde.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.